The present invention relates to a system and method for the treatment of disorders of the vasculature. More specifically, a system and method for treatment of abdominal aortic aneurysm and the like, which is a condition manifested by expansion and weakening of the aorta below the diaphragm. Such conditions require intervention due to the severity of the sequalae, which frequently is death. Prior methods of treating aortic aneurysm have consisted of invasive surgical methods with graft placement within the aorta as a reinforcing member of the artery. However, such a procedure requires a surgical cut down to access the vessel, which in turn can result in a catastrophic rupture of the aneurysm due to the decreased external pressure from the organs and tissues surrounding the aorta, which are moved during the procedure to gain access to the vessel. Accordingly, surgical procedures have a high mortality rate due to the possibility of the rupture discussed above in addition to other factors. Other factors can include poor physical condition of the patient due to blood loss, anuria, and low blood pressure associated with the aortic abdominal aneurysm. An example of a surgical procedure is described in a book entitled Surgical Treatment of Aortic Aneurysms by Denton A. Cooley, M. D., published in 1986 by W.B. Saunders Company.
Due to the inherent risks and complexities of surgical procedures, various attempts have been made in the development of alternative methods for deployment of grafts within aortic aneurysms. One such method is the non-invasive technique of percutaneous delivery by a catheter-based system. Such a method is described in Lawrence, Jr. et al. in “Percutaneous endovascular graft: experimental evaluation”, Radiology (May 1987). Lawrence described therein the use of a Gianturco stent as disclosed in U.S. Pat. No. 4,580,568. The stent is used to position a Dacron fabric graft within the vessel. The Dacron graft is compressed within the catheter and then deployed within the vessel to be treated. A similar procedure has also been described by Mirich et al. in “Percutaneously placed endovascular grafts for aortic aneurysms: feasibility study,” Radiology (March 1989). Mirich describes therein a self-expanding metallic structure covered by a nylon fabric, with said structure being anchored by barbs at the proximal and distal ends.
One of the primary deficiencies of the existing percutaneous devices and methods has been that the grafts and the delivery catheters used to deliver the grafts are relatively large in profile, often up to 24 French and greater, and stiff in bending. The large profile and bending stiffness makes delivery through the irregular and tortuous arteries of diseased vessels difficult and risky. In particular, the iliac arteries are often too narrow or irregular for the passage of a percutaneous device. Because of this, non-invasive percutaneous graft delivery for treatment of aortic aneurysm is not available to many patients who would benefit from it.
Another contraindication for current percutaneous grafting methods and devices is a vessel treatment site with high neck angulation which precludes a proper fit between the graft and the vessel wall. An improper fit or seal between the graft and the vessel wall can result in leaks or areas of high stress imposed upon the diseased vessel which lead to reduced graft efficacy and possibly rupture of the aneurysm.
While the above methods have shown some promise with regard to treating abdominal aortic aneurysms with non-invasive methods, there remains a need for an endovascular graft system which can be deployed percutaneously in a small diameter flexible catheter system. In addition, there is a need for a graft which conforms more closely to the contours of an aortic aneurysm which are often quite irregular and angulated and vary from patient to patient. The present invention satisfies these and other needs.